climate-driven trends in contemporary ocean productivity michael behrenfeld oregon state university...

Climate-driven Trends in Contemporary Ocean Productivity

Michael BehrenfeldOregon State University

Robert O’Malley Jorge Sarmiento Wayne EsaiasDon Shea Gene Feldman Robert FrouinDave Siegel Allen Milligan Compton TuckerEmmanuel Boss Ricardo Letelier Dorota KolberToby Westberry James Randerson Nathan PollackChuck McClain Christopher Field Stephane MaritorenaPaul Falkowski Sietse Los

or

“The World According to SeaWiFS”

• Biospheric NPP increased 6 Pg from 1997 El Nino to 1999 La Nina, with clearest response in oceans

• In most central ocean gyres, chlorophyll concentrations decreased between 1997 and 2003

• Declines in mid-ocean gyres chlorophyll associated with increases in sea surface temperature

7 December 2006 Vol. 444 Nature

Tidbits

• Based on Vertically Generalized Production Model (VGPM)

• Initial increase = 1,930 TgC/yr

• Subsequent decrease = 190 TgC/yr

• Global trends dominated by changes in permanently stratified ocean regions (ann. ave. SST < 15oC)

global> 15oC

-200

-150

-100

-50

0

50

100

150 -0.9

-0.7

-0.5

-0.3

-0.1

0.2

0.4

0.6

0.8

1.0

1.2

*

* Multivariate ENSO Index

Low

Latitu

de

SS

T A

nom

aly

SS

T C

han

ges

( 0C

) +3

-1

+2

-2

+1

-3

0

0

-30

+60

-60

+30

NP

P C

han

ges (

%) b

a

cN

PP

NP

PS

ST

SS

T

Tidbits

• Six different coupled climate models• Ocean biological responses to climate warming from industrial revolution to 2050• Marginal sea-ice biome area decreases 42% (N) and 17% (S)• Expansion of low production permanently stratified ocean by 4% (N) to 9.4% (S)• Subpolar gyre biome expands 16% (N) and 7% (S)• Stratification decreases nutrient supply and thus productivity in permanently stratified oceans• Stratification, extended growing season, and sea ice retreat enhance production at high latitudes• Significant shifts in community composition

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

-200

-150

-100

-50

0

50

100

150

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

-200

-150

-100

-50

0

50

100

150

Year1998 2000 2002 2004 2006

Year1998 2000 2002 2004 2006

global> 15oC

< 15oC

…are there alternative explanations?L

ow

Latitu

de

SS

T A

nom

aly

‘98-200

-150

-100

-50

0

50

100

150 -0.9

-0.7

-0.5

-0.3

-0.1

0.2

0.4

0.6

0.8

1.0

1.2‘99‘97 ‘00 ‘01 ‘02 ‘03 ‘04 ‘05 ‘06

Year

• Nutrient-driven changes in NPP

So, what do we really know?....• Satellites measure neither NPP or chlorophyll, they tell us about optics• SeaWiFS has recorded changes in ocean optical properties over vast regions• These changes are clearly linked to effects of climate variability on upper ocean temperature and stratification - not instrument or atmospheric artifacts

• Photo-oxidation of cDOM

• Light-driven changes in photoacclimation

Spectral matching algorithms are a path to a solution…• Do not rely on the ‘bio-optic’ assumption – now known to be wrong• Would allow changes in cDOM photo-oxidation to be detected• Would allow changes in photoacclimation to be detected from Chl:C• Are not optimized with heritage ‘ocean color’ wavebands

Difference in chlorophyll estimates for standard wavelength-ratio and

spectral matching algorithms

cDOM from spectral matching algorithm

•Uncertainty in remote sensing products reflects inadequacy of heritage wavebands for separating different absorbing and scattering components.

Measurement Maturity Index

Des

ired

Tra

ject

ory

1 2 3 4 5 6 7 81

2

3

4

5

6

7

8

Mea

sure

men

t Q

ualit

y In

dex

CZCS (1978-1985)

SeaWiFS(1997 - )

MODIS (2002 - )

VIIRS(2009 - )

AdvancedMission(2013 - )

Ins

uff

icie

nt

for

Cli

ma

te D

ata

Re

co

rd Current trajectory

Cli

ma

te D

ata

R

ec

ord

Qu

ali

ty

KeyFew science products

Extensive science products

* NOTE: MODIS Aqua climate-quality ocean biology data have only been achieved because SeaWiFS data were available for comparison

*

measured operationally

approaches limits on

performance

no known use for measurement

potential science return

SW

IRN

IRV

isib

le

CZ

CS

Se

aW

iFS

MO

DIS

VII

RS

SWIR NIR Visible Ultraviolet

5 nm resolution (335 – 865 nm) 17 aggregate bands

2 SWIRbands

Backup Slides

Su

rface C

hlo

rop

hyll A

nom

aly

(Tg

)

Year1998 2000 2002 2004 2006

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

> 15oC

Contemporary Changes in Ocean Chlorophyll during the SeaWiFS Era

El Nino – La Nina changes

Chlsat vs Chleuphotic

Other NPP models

Chlorophyll and MEI

NPP and MEI update

Zonal temperature changes

Surface chlorophyll updates

The 2006 minimum

Credit really belongs to the Ocean Color Group at NASA Goddard Space Flight Center and Ocean Biology and Biogeochemistry Program at NASA Headquarters

• Biospheric NPP increased 6 Pg from 1997 El Nio to 1999 La Nia, with clearest response in oceans

(C)

(D)

0.01 0.1 1 10 100 1000

Chlorophyll Concentration

0.01 0.1 1 10 100 1000

Rela

tive F

requency

Dep

th-i

nte

gra

ted

Year

1998 2000 2002 2004 2006

-0.012

-0.008

-0.004

0

0.004

0.008

Su

rface C

hlo

rop

hyll

An

om

aly

(Tg

)

global> 15oC

Tidbits

• Three models: VGPM – polynomial VGPM – Eppley CbPM – Chl:C-based growth

• All show 2 primary trends

• Biggest differences is in slope of initial El Nino – La Nina period

Chl

Chl

SS

TSS

TM

atc

hM

ism

atc

h

Chl

Chl

SS

TSS

TVGPM Polynomial

VGPM Eppley

matchup / mismatch

-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

0 20 40 60 80 100 120

-2.3

-1.3

-0.3

0.7

1.7

2.7

Year

1998 2000 2002 2004 2006

MEI

-0.8000

-0.6000

-0.4000

-0.2000

0.0000

0.2000

0.4000

0.6000

0.8000

1.0000

0 20 40 60 80 100 120

subpolar

subtropical

equatorial

global

SST c

hanges

-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0 20 40 60 80 100

-0.1

-0.08

-0.06

-0.04

-0.02

0

0.02

0.04

0.06

0.08

0.1

0 20 40 60 80 100

-0.1

-0.08

-0.06

-0.04

-0.02

0

0.02

0.04

0.06

0.08

0.1

0 20 40 60 80 100

-0.1

-0.08

-0.06

-0.04

-0.02

0

0.02

0.04

0.06

0.08

0.1

0 20 40 60 80 100

SeaWiFS time series – sequential months

Chlo

rophyll

anom

alie

s

All bins

Global

> 15C

< 15C

-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0 20 40 60 80 100

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

0 20 40 60 80 100

SeaWiFS time series – sequential months

Su

rface C

hlo

rop

hyll A

nom

aly

(Tg

)

Quality and Maturity DefinitionsQuality and Maturity Definitions

Measurement Maturity Index1 = No known operational use for measurement2 = Parameter identified as having potential for operational significance 3 = Operational significance demonstrated through simulations4 = Pathfinder mission launched. Need for long term record widely accepted 5 = Pilot decision support tool (DST) use of space-based measurements6 = Space ops over sustained period. Adds value to DSTs.7 = Ready for transfer to operational use 8 = Measured operationally. Used operationally in existing DSTs.

Measurement Quality Index1 = Measurement identified as potentially providing significant science return2 = Initial measurements produced and calibrated3 = Geophysical, biological, or chemical properties inferred or estimated from

calibrated measurements4 = Geophysical, biological, or chemical properties inferred or estimated from

calibrated measurements and validated5 = Significant improvement in calibration, spatial resolution, spectral resolution,

temporal revisit, and/or spatial coverage over initial measurements6 = Second significant improvement in calibration resolution, temporal revisit,

and/or spatial coverage over initial measurements7 = Further significant improvement in calibration resolution, temporal revisit,

and/or spatial coverage over initial measurements8 = Measurement approaches theoretical or practical limits on performance